Another 77,500 units were previously recalled in three announcements dating back to 2007. The air exchangers were made by Venmar Ventilation between 2002 and 2009 and were sold under a variety of brand names, including Bryant, Carrier, NuTone, Frigidaire, Maytag, Tappan, Heil, Westinghouse, Rheem, Sears (SHLD) and York. They were sold with and without a heat-recovery feature.

So far, 30 fires have been reported to have been caused by the air exchangers, resulting in more than $1.1 million in property damage. The recall was expanded after four new incidents were reported. The motor can overheat and start fires, the CPSC said.

If you have one of the recalled air exchangers, you are urged to shut it off immediately and call Venmar at (866) 441-4645 to schedule a free inspection and repair.

This latest recall affects 108,000 units sold in the U.S. and 207,000 in Canada, the CPSC said, and brings the total number recalled in the U.S. to more than 185,000.